U.S. patent application number 10/175131 was filed with the patent office on 2004-01-29 for method and apparatus for supporting a substrate.
Invention is credited to Morini, John E., Pham-Van-Diep, Gerald.
Application Number | 20040016113 10/175131 |
Document ID | / |
Family ID | 29733782 |
Filed Date | 2004-01-29 |
United States Patent
Application |
20040016113 |
Kind Code |
A1 |
Pham-Van-Diep, Gerald ; et
al. |
January 29, 2004 |
Method and apparatus for supporting a substrate
Abstract
An apparatus and method for performing operations on an
electronic substrate includes a frame, a transportation system that
moves the substrate through the apparatus, a substrate support
system coupled to the frame that supports the substrate during a
manufacturing operation on the substrate, wherein the substrate
support system includes a deformable material, and a device coupled
to the frame that performs an operation on a surface of the
substrate. Manufacturing operations are performed on the substrate
while the substrate is substantially evenly supported by the
deformable material.
Inventors: |
Pham-Van-Diep, Gerald;
(Hopkinton, MA) ; Morini, John E.; (Douglas,
MA) |
Correspondence
Address: |
Thomas M. Sullivan, Esq.
Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C
One Financial Center
Boston
MA
02111
US
|
Family ID: |
29733782 |
Appl. No.: |
10/175131 |
Filed: |
June 19, 2002 |
Current U.S.
Class: |
29/729 |
Current CPC
Class: |
Y10T 29/5313 20150115;
H05K 3/1216 20130101; H05K 13/0069 20130101 |
Class at
Publication: |
29/729 |
International
Class: |
B23P 019/00 |
Claims
What is claimed is:
1. An apparatus for performing operations on at least one surface
of an electronic substrate having a first surface and a second
surface, the apparatus comprising: a frame; a transportation system
that moves the substrate through the apparatus; a substrate support
system coupled to the frame that supports the substrate during an
operation on the substrate, wherein the substrate support system
includes a deformable material; and a device coupled to the frame
that performs an operation on a surface of the substrate.
2. The apparatus of claim 1 wherein the substrate support member is
moveable from a lowered position to a raised position, wherein in
the raised position the deformable material contacts a side of the
electronic substrate.
3. The apparatus of claim 2 wherein the deformable material is a
low durometer gel.
4. The apparatus of claim 2 wherein the deformable material is a
rheomagnetic fluid.
5. The apparatus of claim 4 wherein the substrate support member
includes at least one electromagnetic cavity and wherein the
rheomagnetic fluid is at least partially disposed in the
electromagnetic cavity.
6. The apparatus of claim 5 further comprising a thin-walled tube
that houses the rheomagnetic fluid.
7. The apparatus of claim 6 wherein the at least one
electromagnetic cavity is a plurality of electromagnetic cavities,
and wherein a tube of rheomagnetic fluid is disposed in each of the
plurality of electromagnetic cavities.
8. The apparatus of claim 1, wherein the device is a stencil and
the substrate is a circuit board.
9. A method of performing an operation on an electronic substrate,
the method comprising: loading the substrate into a processing
machine; supporting the substrate with a deformable material that
conforms to a surface of the electronic substrate; performing a
manufacturing operation on the substrate; and removing the
substrate from the processing machine.
10. The method of claim 9 wherein the electronic substrate is a
circuit board.
11. The method of claim 7 further comprising returning the
deformable material to a home position after the substrate is
removed from the processing machine.
12. The method of claim 9 wherein the deformable material is a low
durometer gel.
13. The method of claim 9 wherein the deformable material is a
rheomagnetic fluid at least partially disposed in an
electromagnetic cavity.
14. The method of claim 13 further comprising energizing the
electromagnetic cavity to solidify the rheomagnetic fluid at least
partially disposed in the electromagnetic cavity.
15. The method of claim 14 further comprising de-energizing the
electromagnetic cavity.
16. An apparatus for supporting an electronic substrate during a
manufacturing operation, the apparatus comprising: a frame; means,
coupled to the frame, for supporting electronic substrates,
including a deformable material which conforms to a surface of the
substrate to be supported during manufacturing.
17. The apparatus of claim 16 wherein the deformable material is a
low durometer gel.
18. The apparatus of claim 16 wherein the deformable material is a
rheomagnetic fluid.
19. The apparatus of claim 18 further comprising means for
solidifying the rheomagnetic fluid.
20. The apparatus of claim 16, further comprising a stencil and a
device for depositing material on the stencil.
Description
FIELD OF THE INVENTION
[0001] The invention relates to apparatus and methods for
processing substrates such as circuit board assemblies, and more
specifically to apparatus and methods for supporting a circuit
board during the printing of solder paste on the circuit board,
dispensing of material on the circuit board, placing of components
on the circuit board, or some other operation.
BACKGROUND OF THE INVENTION
[0002] The manufacturing of circuit boards involves many processes,
one of which is surface mounting electrical components to the
circuit boards. To surface mount components to a first surface of a
circuit board, a dispenser deposits solder paste or adhesive onto
the first surface of the circuit board, and then components are
pressed against the solder paste or adhesive. After the first side
of the circuit board has been populated with components, the board
is inverted and the process is repeated to surface mount components
to the second side of the board. The solder paste dispenser is
typically a stenciling machine, and typically a turret-type device
presses the components into the solder paste or adhesive.
[0003] When a circuit board is subjected to these manufacturing
processes, it is often desirable to uniformly support the board
across the lower surface so that the upper surface remains in
substantially the same plane while a force is applied to the
topside of the circuit board. Known means of supporting a circuit
board during manufacturing operations are described in Beale, U.S.
Pat. No. 5,157,438; Rossmeisl, U.S. Pat. No. 5,794,329; Barozzi,
U.S. Pat. No. 4,936,560; Dougherty, U.S. Pat. No. 5,152,707; and
Hertz, U.S. Pat. No. 6,264,187.
SUMMARY OF THE INVENTION
[0004] In general, in one aspect, the invention provides an
apparatus for performing operations on a surface of an electronic
substrate. The apparatus includes a frame, a transportation system
that moves the substrate through the apparatus, a substrate support
system that supports the substrate during an operation on the
substrate and that includes a deformable material, and a device
coupled to the frame that performs an operation on the surface of
the substrate.
[0005] Implementations of the invention may include one or more of
the following features. The support system of the apparatus can be
moveable from a lowered position to a raised position such that in
the raised position, the deformable material contacts a side of the
electronic substrate.
[0006] Further implementations of the invention may include one or
more of the following features. The deformable material can be a
low durometer gel. Alternatively, the deformable material can be a
rheomagnetic fluid. The support member may include an
electromagnetic cavity and the rheomagnetic fluid may be at least
partially disposed in the electromagnetic cavity. Thin-walled tubes
can be used to contain the rheomagnetic fluid. The support member
can include a plurality of electromagnetic cavities, and a tube of
rheomagnetic fluid can be disposed in each of the plurality of
electromagnetic cavities. The electromagnetic cavities can be
energized to solidify the rheomagnetic fluid.
[0007] In general, in another aspect, the invention provides a
method of performing an operation on an electronic substrate. The
method includes loading the substrate into a processing machine,
supporting the substrate with a deformable material that conforms
to a surface of the substrate, performing a manufacturing operation
on the substrate, and removing the substrate from the processing
machine. The electronic substrate can be a circuit board. The
deformable material can be returned to a home position after the
substrate is removed from the processing machine.
[0008] Generally, in another aspect, the invention provides an
apparatus for supporting an electronic substrate during a
manufacturing operation. The apparatus includes a frame and means
coupled to the frame for supporting electronic substrates,
including a deformable material which conforms to a surface of the
substrate to be supported during manufacturing.
[0009] Implementations of the invention may include one or more of
the following features. The supporting means may include a low
durometer gel as the deformable material to support the substrate.
Alternatively, the supporting means may include a rheomagnetic
fluid as the deformable material. The supporting means can include
further means for solidifying the rheomagnetic fluid.
[0010] The invention will be more fully understood after a review
of the following figures, detailed description and claims.
BRIEF DESCRIPTION OF THE FIGURES
[0011] For a better understanding of the present invention,
reference is made to the drawings which are incorporated herein by
reference and in which:
[0012] FIG. 1 is a top view of a printing apparatus in accordance
with one embodiment of the invention;
[0013] FIG. 2A is a schematic diagram of support gel in a
preparation stage in one embodiment of the invention;
[0014] FIG. 2B is a schematic diagram of support gel in a conformed
stage in one embodiment of the invention;
[0015] FIG. 2C is a schematic diagram of support gel in a
post-loaded stage in one embodiment of the invention;
[0016] FIG. 3A is a schematic diagram of rheomagnetic fluid in a
pre-energized phase in one embodiment of the invention;
[0017] FIG. 3B is a schematic diagram of rheomagnetic fluid in a
loaded phase in one embodiment of the invention; and
[0018] FIG. 3C is a schematic diagram of rheomagnetic fluid in an
energized phase in one embodiment of the invention.
[0019] FIG. 4 is a schematic diagram of a top view of the
rheomagnetic fluid support system in one embodiment of the
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0020] Embodiments of the present invention are described below
with reference to screen printers or stencil printers that print
solder paste onto circuit boards. As understood by those skilled in
the art, embodiments of the present invention can be used with
electronic substrates other than circuit boards, such as electronic
components, and with machines other than screen printers such as
pick and place machines or dispensing machines.
[0021] Referring to FIG. 1, internal components of a printer 5 in
accordance with one embodiment of the invention that applies solder
paste to circuit boards are shown. The printer is an improvement
over screen printers described in U.S. Pat. No. 5,794,329, which is
hereby incorporated by reference.
[0022] As shown in FIG. 1, the printer 5 includes a tractor feed
mechanism 12, edge tractor mechanisms 14, a rigid support table 16,
a board support mechanism 20, a moveable gantry 24, a controller
23, a squeegee/adhesive applicator 28, and a camera 30 carried on a
carriage 32. The support mechanism 20 is located on and attached to
the support table 16. The camera 30 carried on the carriage 32 is
moveable along the gantry 24 in a linear X-axis of motion. The
gantry 24 is moveable along tracks 26 in a linear Y-axis of motion.
The squeegee/adhesive applicator 28 is attached to the printer 5 in
a position above the level of the circuit board 10.
[0023] Boards 10 fed into the printer 5 usually have a pattern of
pads or other, usually conductive surface areas onto which solder
paste will be deposited. When directed by the controller of the
printer, the tractor feed mechanism 12 supplies boards 10 to a
location where the camera 30 records an image of the circuit board
10. The image is sent to the controller, which signals for the edge
tractor mechanisms 14 to shuttle the board 10 to a second location
over the rigid support table 16, beneath a solder stencil. Once
arriving at a position over the support table 16, the circuit board
10 is in place for a manufacturing operation. To successfully
perform operations on the board 10, the board 10 is supported by
the support mechanism 20. The support mechanism 20 is raised from
beneath the circuit board 10 at the direction of the controller.
When the solder stencil and the circuit board 10 are aligned
correctly, the stencil is lowered toward the board 10 for
application of the solder paste or the board can be raised toward
the stencil by the support mechanism. The squeegee/adhesive
applicator 28, positioned above the circuit board 10, is shown in
phantom in FIG. 1. The adhesive applicator 28 can vary the amount
of solder paste or adhesive delivered on the stencil and applied by
the squeegee. The squeegee 28 wipes across the stencil, thereby
pushing solder paste through the stencil onto the board 10. After
solder paste has been deposited on the circuit board 10, the
support mechanism 20 moves downward away from the position of the
board, under control of the controller. The controller then
controls movement of the board 10 to the next location using the
tractor mechanism 18, where electrical components 11 will be placed
on the board.
[0024] As discussed, the circuit board 10 enters on the tractor
feed mechanism 12 and stops when in a position over the table 16
where deposition of solder paste will occur. Throughout the process
of printing the solder paste on the circuit board 10, a force is
applied to a top surface of the board 10 by the squeegee. In order
for the solder paste to be applied evenly, the circuit board 10 is
supported using the support mechanism 20 to oppose the force being
applied to the topside of the board 10. In embodiments of the
invention, the support mechanism 20, which is attached to the
printer above the surface of the table 16, includes a deformable
material 42 in a support bed 40. The entire support mechanism 20 is
attached to the printer frame in such a way that it can be raised
to the surface of the circuit board 10, allowing the deformable
material 42 to conform to the underside topography of the board 10
during printing. In this way, the deformable material 42 evenly
supports the underside of the circuit board 10 due to its ability
to conform to the topography of the circuit board 10.
[0025] Referring to FIGS. 2A-2C, the support mechanism 20 is shown
in greater detail. The support mechanism 20 includes a base 44, a
housing 40 and a deformable material 42. The deformable material 42
is a low durometer gel contained in the housing 40, which functions
as a support bed for containing the deformable material. In one
embodiment, the low durometer gel 42 is a polyurethane gel,
manufactured and distributed by Northstar Polymer, LLC, located in
Minneapolis, Minn. under part no. MPP-V37A. In FIG. 2A, the support
mechanism is shown moving in the direction of arrow 41 toward a
circuit board 10 to support the board 10 in the printer 5. The
underside of the circuit board is populated with electrical
components 11.
[0026] FIG. 2B shows the support mechanism 20 in contact with the
board 10 after a print operation has occurred. In FIG. 2B, a
stencil 45 is still in contact with the board 10. Under compression
caused by the contact of the gel 42 with the board 10, the gel 42
conforms to the underside topography of the circuit board 10, as
shown in FIG. 2B, to provide evenly distributed support to the
circuit board 10. The gel 42 is of a consistency such that it
remains contained within the housing 40 even while under
compression. Controlled by the controller, the gel 42 and support
bed 40 are retracted from the surface of the board 10 in the
direction of arrow 43 at the completion of processing the circuit
board 10, and the entire support mechanism 20 returns to a home
position, shown in FIG. 2C, where it will remain until the next
board 10 is aligned for processing. As shown in FIG. 2C, the low
durometer gel 42 returns to a relaxed state when the support
mechanism 20 is in the home position. The low durometer gel 42 is
then ready to conform to a board topography during a next print
cycle.
[0027] Alternatively, in another embodiment of the invention, which
will now be described with reference to FIGS. 3A-3C and FIG. 4, a
support mechanism 120 may be used to support a circuit board during
printing in place of support mechanism 20, previously described.
The support mechanism 120 includes a base 44, electromagnetic
cavities 64, magnetic windings 65 and a deformable material 142.
The deformable material 142 is a rheomagnetic fluid contained in
thin-walled tubes 62, which may be made of latex, that are
partially disposed in the electromagnetic cavities 64. In one
embodiment, the rheomagnetic fluid is a mixture of small magnetic
particles such as iron, and a viscous fluid such as oil or water,
manufactured and available from Lord Corporation of Cary, N.C.
under part nos. including MRF-132AD, MRF-132LD, MRF-241GS,
MRF-240B5 and MRF-336AG. In one embodiment, the electromagnetic
cavities are made of a magnetic material, such as iron. Common
magnetic windings 65 line the base of the electromagnetic cavities
64. The electromagnetic cavities 64 are attached via connecting
wires 66 to a source that provides electric current under control
of the controller. As shown in FIG. 4, the electromagnetic cavities
64 can be aligned across the length of the base 44 of the support
mechanism 120.
[0028] The support mechanism 120 operates as follows. A circuit
board 10, having an underside populated with electrical components
11, is positioned over table 16 for the deposition of solder paste.
The support mechanism 120 is moved under the control of the
controller in the direction of arrow 141 until the rheomagnetic
material contacts the underside of circuit board 10. While the
support mechanism 120 approaches the underside of circuit board 10,
the rheomagnetic fluid 142 is in a free, or relaxed state. In the
relaxed state, the rheomagnetic fluid 142 easily conforms to the
topography of the board 10 upon contact with the board 10. While
the rheomagnetic fluid 142 is in contact with the board 10, the
electromagnetic cavities 64 are energized with an electric current
via connecting wires 66, which are also connected to a DC power
source. The magnetic field is proportional to the direction and
intensity of the electric current in the magnetic winding 65.
Enough current must be provided to generate a magnetic field strong
enough to align the particles in the rheomagnetic fluid 142. Energy
from the electromagnetic cavities 64 transforms the tubes 62 of
rheomagnetic fluid 142 from a fluid state to a rigid state. While
in the rigid state, the rheomagnetic fluid 142 provides sufficient
board support during manufacturing operations.
[0029] The configuration of the rheomagnetic fluid 142 when
energized is such that it rigidly supports the surface of the board
10, whether the board 10 is populated with electrical components or
not. The rheomagnetic fluid 142 will remain energized, or in a
rigid state for as long as the electromagnetic cavities 64 remain
energized with an electric current as shown in FIG. 3C. The
rheomagnetic fluid remains energized in a shape conforming to a
first circuit board 10 so that many circuit boards 10 having the
same topography as the first circuit board 10 can be mass-produced
without de-energizing and re-energizing the rheomagnetic fluid 142.
Upon completion of processing of a board 10, the controller directs
the support mechanism 120 to the lowered position in the direction
of arrow 143.
[0030] If it is desired to process a second type of board, the
electromagnetic cavities 64 are de-energized, thereby returning the
rheomagnetic fluid 142 to a fluid state. The system resets for
another print cycle when the support mechanism 120 is returned to a
home position. The rheomagnetic fluid 142 is re-configured to
support another set of circuit board assemblies with a different
configuration of electrical components 11 by pressing the
rheomagnetic fluid against the undersurface of a new circuit board
10 and energizing the electromagnetic cavities 64 with electric
current once again.
[0031] In the embodiments of the present invention described above,
the low durometer gel when used as the deformable material fills
the housing container completely. As understood by those skilled in
the art, other configurations may include strips of low durometer
gel contained in the support housing, or other appropriate and
strategic configurations of the gel that amply support the
underside of the circuit board.
[0032] In embodiments of the present invention described above, the
rheomagnetic fluid used as a deformable material is contained in an
assembly of electromagnetic cavities, all of which comprise the
support system. As understood by those skilled in the art, other
configurations may include a single electromagnetic cavity
containing rheomagnetic fluid such that the single container of
rheomagnetic fluid is sufficiently energized to conform to the
surface of the boards. The assembly of electromagnetic cavities may
further be aligned across the width of the base of the support
mechanism. In still further embodiments of the present invention, a
connecting wire is attached to each of the electromagnetic cavities
to provide electric current that energizes the electromagnetic
cavities, which thereafter energizes the rheomagnetic fluid to make
it rigid. As understood by those skilled in the art, other
configurations may include a single set of connecting wires that
provides electric current to all of the electromagnetic cavities in
the assembly.
[0033] In still further embodiments of the present invention, the
support mechanism is attached to the printer frame so that it moves
in an upward direction toward the underside of the circuit board
during manufacturing, when directed by the controller. As
understood by those skilled in the art, other configurations may
include a support mechanism in a fixed position whereby the boards
are lowered to the deformable material of the support mechanism
during manufacturing.
[0034] Having thus described at least one illustrative embodiment
of the invention, various alterations, modifications and
improvements will readily occur to those skilled in the art. Such
alterations, modifications and improvements are intended to be
within the scope and spirit of the invention. Accordingly, the
foregoing description is by way of example only and is not intended
as limiting. The invention's limit is defined only in the following
claims and the equivalents thereto.
* * * * *